Apparatus for making pressed board

ABSTRACT

In manufacturing pressed boards, a flowable mixture of thermosetting resinous material and filler is blown through one or more nozzles into a converging throat formed by a pair of relatively inclined perforated conveyor bands in which the mixture is compacted into a continuous, coherent but preferably still pliable web by the application of heat to preset the resinous material thereof. The web may be immediately converted into a rigid board by being led, without intermediate cooling, into a continuously working press for final condensation of the resin; on the way to that press it may be subjected to a finishing operation, as by adhesion of preheated strips of paper or other coverings to its still tacky surfaces.

United States Patent [1 1 Axer et al.

[ 1 APPARATUS FOR MAKING PRESSED BOARD [75] Inventors: Heinrich Axer.Nettetal; Gerd Roth,

Kevelaer. both of Germany [73] Assignee: G. Siempelkamp & Co., Krefeld.

Germany [22] Filed: July 30, 1973 [21] Appl. No.: 383.730

156] References Cited UNITED STATES PATENTS 1.185.399 5/1916 Hayes425/371 1.423.020 7/1922 Pokornym. 425/371 2.042.243 5/1936 Watson425/335 X 2.460.566 2/1949 Brown et a1. 425/371 X 2.623.239 12/1952Fischbcin n 425/224 X 2.779.969 2/1957 Bose 425/371 2.830.648 4/1958Huddoxm 425/115 X 2.872.965 2/1959 Sisson 425/335 2.975.470 3/1961Snclson et a1 1 425/371 X 3.044.111 7/1962 Caughey 425/224 1 1 Sept. 9,1975 Primary E.\ uml'nerAl Lawrence Smith Ass/51ml! E.\'uniinerJ. T.Zatarga Attorney. Agent. or Fi'rmKarl F. Ross; Herbert Dubno [57]ABSTRACT In manufacturing pressed boards. a flowable mixture ofthermosetting resinous material and filler is blown through one or morenozzles into a converging throat formed by a pair of relatively inclinedperforated conveyor bands in which the mixture is compacted into acontinuous. coherent but preferably still pliable web by the applicationof heat to preset the resinous material thereof. The Web may beimmediately converted into a rigid board by being led. withoutintermediate cooling. into a continuously working press for finalcondensation of the resin; on the way to that press it may be subjectedto a finishing operation. as by adhesion of preheated strips of paper orother coverings to its still tacky surfaces.

8 Claims. 9 Drawing Figures RES/N Q- FlLLER PATENTED 35F 9 3975 saw 2 0r4 FIG. 2

HEATING FLUID PATENTED W5 SHEET 3 0F {1 o w a e edd wi Llr 4 e m V Q WWQUI A\ PATENTEBSEP ems 3 904,336

sum u 0F 9 AIR HEA TER 22a H54 715 J m ER 274 FIG. 9

APPARATUS FOR MAKING PRESSED BOARD FIELD OF THE INVENTION Our presentinvention relates to an apparatus for making pressed board of the typein which a binder of thermo-setting resinous material is blended with afiller and the resulting mixture is then compacted into sheet or plateform, the resin being subsequently cured to convert the compacted bodyinto a solid board. Depending on the nature of the filler, which couldconsist of wood chips and/or cellulosic or other fibers, these pressedboards are generally known as chipboards or fiberboards.

BACKGROUND OF THE INVENTION In the conventional manufacture of suchpressed boards, the mixture of binder and filler is compacted in thecold state and later subjected to heat and pressure for setting theresin. Prior to such setting, the compacted body has only limitedmechanical strength and is, therefore, difficult to handle. Problemsexist, accordingly, in transporting such sheets or plates to a flatpress(e.g. one of the multilevel type) for final shaping and setting.

OBJECTS OF THE INVENTION An important object of our present invention,therefore, is to provide means for converting the aforedescribed mixtureinto an intermediate product of manufacture which is easy to handle andfrom which pressed board can be made by conventional treatment.

Another object is to provide an apparatus for producing, in a singleoperation, a continuous web of this character from which solid plates orboards ofa desired size can be obtained merely by cutting.

It is also an object of our invention to provide means in such anapparatus for imparting a desired finish to a web of the type referredto, as by adhering strips of paper or other covering material to eitheror both surfaces thereof.

SUMMARY OF THE INVENTION We have found, in accordance with our presentinvention, that an easily manipulable and coherent intermediate productin the manufacture of pressed board can be produced in an apparatus inwhich a flowable mixture of thermosetting resinous material and filleris introduced by one or more nozzles into a converging throat defined bya pair of perforated, endless conveyor bands with relatively inclinedconfronting surfaces, the perforations serving for the escape of acarrier fluid (usually air) which entrains the components of themixture. The flowable mixture entering the throat is subjected to theaction of heating means for at least partly setting the resinous binderthereof during compaction of the mixture between the conveyor bands intoa continuous and coherent web. The term setting" (or presetting), asherein used, encompasses both condensation and polymerization.

The heating of the mixture in the converging throat may be carried outdielectrically, as with the aid of electrodes constituted at least inpart by a pair of pressure plates enveloped by the conveyor bands; thesepressure plates could also be formed with channels for the circulationof a hot fluid therethrough. Alternatively, or in conjunction therewith,the carrier fluid itself could be preheated ahead of the nozzle ornozzles through which the mixture is entrained into the convergingthroat.

Depending on the degree of heating, which in general should be roughlycommensurate with the degree of compression the mixture undergoesbetween the conveyor bands. the setting of the resinous material may becarried to only partial or substantially full completion within thecompacting stage. In either case, the mass issuing from that stage willhave the shape of a coherent, continuous web which can then be furtherconsolidated, with or without additional heating, in a continously orintermittently operating press.

Pursuant to a further feature of our invention. final pressing andsetting is carried out in a continuously operating stage adjoining thecompacting stage so as to receive the web issuing from the narrow end ofthe throat thereof. The transition from the compacting stage to thefinal stage should take place without significant reduction in webtemperature in order to make the setting process chemically continuous.For this purpose, if the two compression stages are separated by afurther treatment stage, the latter should be provided with supplementalheating means for at least maintaining the web temperature at the valueit has on exiting from the throat. If the intermediate stage is afinishing stage, designed to apply decorative or protective coveringssuch as paper strips, veneers or the like to either or each of the stilltacky web surfaces for adhesion thereto, the desired maintenance of orincrease in temperature level is advantageously accomplished bypreheating the covering material prior to its application to the web.

In cases where the filler consists predominantly of narrow particles,such as flat chips or short filaments, the setting process may not beuniform ifthesc particles are randomly distributed within the resinmatrix or binder. We therefore prefer to subject the particles upontheir entrance into the throat to an orienting force which makes themlie substantially transversely to the direction of web growth or motion.This orientation may be accomplished with the aid of vibrators thatagitate the oncoming particles, coated with resinous material, at thepoint where they impinge upon the mass already present within thethroat.

DESCRIPTION OF THE DRAWINGS The above and other features will now bedescribed with reference to the accompanying drawing in which:

FIG. 1 is a side-elevational view of a compacting stage forming part ofan apparatus according to our invention;

FIG. 2 is an enlarged view of the detail ll of FIGv 1;

FIG. 3 is a view similar to that of FIG. 1, illustrating a modification;

FIG. 4 is an enlarged view of the detail IV of FIG. 3;

FIG. 5 is a side-elevational view of an apparatus including a finalcompression stage besides a preliminary compacting stage of the typeshown in FIG. 1;

FIG. 6 is an enlarged view of the detail VI of FIG. 5;

FIG. 7 is a simplified overall view, drawn to a re duced scale, ofasystem as shown in FIG. 5, with incorporation of an intermediatefinishing stage;

FIG. 8 is a view similar to FIG. 7, illustrating a modified finishingstage; and

FIG. 9 is another view similar to FIG. 7, illustrating a furthermodification of the finishing stage.

SPECIFIC DESCRIPTION In FIGS. 1 and 2 we have shown a compacting stage 1for a flowable mixture of resinous binder and filler, such as wood chipsadmixed with two interacting components of a thermosetting resin (e.g.phenolformaldehyde) along with a catalyst therefor. The mixture issupplied by one or more nozzles 6 through which it is introduced withthe aid ofa carrier gas represented diagrammatically by an arrow G.Nozzle 6 opens into a narrowing inlet guide 9, formed from stationaryplates, which terminates at the broad end of a converging throat 8defined by an upper compression plate 2, a lower compression plate 3 andtwo endless screen-type conveyor bands 4, 5 respectively enveloping theplates 3 and 2. The plates 2 and 3 are adjustably supported onrespective plungers 32, 33 which may be hydraulically actuated to varythe effective separation of the plates and of the conveyor bands, i.e.the width of the throat 8. Upon the escape of the entraining carrier gasthrough the interstices of conveyor bands 4 and 5, the mixture of binderand filler leaves the throat 8 at its narrow end in the direction ofarrow 7 as a continuous, coherent web illustrated at 17 in FIG. 5.

In order to impart the necessary coherency to the web, the mixturecompacted in throat 8 is subjected to the action of heating means 10,here shown as three mutually insulated heating units inserted in thecompression plates 2 and 3 along the conveyor path. As particularlyillustrated for the right-hand unit, each of these units comprises ahigh-frequency generator 11 working into an amplifier 12 whose outputenergizes a pair of electrodes 13, 14 having confronting sides in linewith corresponding surfaces of the compression plates. If individualadjustment of the heating effect at different locations is not required,the plates 2, 3 may themselves be designed as heating electrodes.

As shown in FIGS. 3 and 4, the heaters could be replaced by channels 15in compression plates 2 and 3, these channels being externallyinterconnected by nonillustrated manifolds for the circulation of aheating fluid therethrough.

As indicated in FIG. 7, the carrier gas (e.g. air) blown through nozzle6 may be preheated at 34 to supply all or part of the heat needed for atleast presetting the resinous material of the injected mixture.

In FIG. 5 we have shown the compaction stage 1 immediately followed by afinal compression stage 16, comprising a pair of endless conveyors 35,36, which in this case may be continuous steel bands or the like,entrained in the direction of the arrows by belts 37, 38 supported onrespective pairs of beams 39, 40 (only one beam of each pair beingvisible). The lower beams 40 carry between them a set of rollers 41arrayed in a horizontal plane to guide the upper run of band 36 and belt38 which form a bed for the web 17 issuing from stage 1. The upper beams39 similarly carry rollers 42 which are arrayed along a curved surfaceto guide the lower run of belt 37 and band 35 along a path whichapproaches the bed surface so as to compress the oncoming web 17 to areduced thickness. Rollers 41 and 42 may also be heated, as indicated onthe drawing, e.g. by the passage of a hot fluid therethrough. The finalthickness of the compressed web may be adjusted with the aid of plungers43, which again may be hydraulically actuated, from which the upper beampair 39 is suspended.

FIG. 5 also shows vibrators 23 at the entrance end of throat 8, i.e. inthe position of the first heater 10 of HG. 1, designed to promote atransverse orientation of resin-coated particles 44 (see FIG. 6) blowninto the throat 8.

In FIG. 7 we have illustrated a finishing stage 18 disposed between thetwo compression stages 1 and 16. This finishing stage comprises a pairof rollers 19a, 19b from which strips 19 of paper or other suitablecovering material are continuously deposited on the tacky upper andlower surfaces of web 17 with the aid of nonillustrated guide andpressure rollers. For reasons outlined above, the paper coming fromrollers 19a and 19b is preheated by radiators 22a, 22b so as to maintainthe temperature of the web 17 substantially constant or even increasingas the web passes from stage 1 to stage 16.

FIG. 8 shows a similar arrangement wherein, however, the coveringmaterial 19' placed on the web surfaces consists of fiber layers, thefibers being blown through conduits 24a, 24b onto the surfaces ofcontinuously rotating drums 25a, 25b heated by radiators 22a and 22b.

As shown in FIG. 9, stage 18 comprises a pair of endless upper and lowerconveyors 26a, 26b whose upper runs are loaded with stacks of veneers 20delivered, one by one, to the two web surfaces along curved guide plates27a, 27b; devices 2201 and 22b confront these guide plates so that theveneers 20 are preheated on passing between these radiators and theguide plates.

Naturally, various types of heating means may be used for compressionstages 1 and 16 as well as for in termcdiate stage 18.

We claim:

1. in an apparatus for making pressed board from thermosetting resinousmaterial and filler, in combination:

a pair of perforated, endless conveyor bands with generally horizontal,relatively inclined confronting surfaces forming a converging throatbetween them;

nozzle means adjacent said conveyor bands for con tinuously blowing asubstantially horizontal stream of thermosetting resinous material andfiller entrained by a carrier fluid into said threat from the broad endthereof;

heating means at said throat for at least partly setting said resinousmaterial during compaction of the mixture between said conveyor bandsinto a continuous and coherent web; continuously operating pressadjoining said conveyor bands at the narrow end of said throat forreceiving said web therefrom and further compacting same with finalsetting of said resinous material; and

finishing stage inserted between said conveyor bands and said press,said finishing stage being provided with supplemental heating means forat least maintaining the temperature of the web issuing from saidthroat.

2. The combination defined in claim 1 wherein said conveyor bands areprovided with respective pressure plates for compacting the mixture ofresinous material and filler.

3. The combination defined in claim 2 wherein said pressure plates areprovided with channels, said heating 7. The combination defined in claim1 wherein said finishing stage includes a supply of covering materialfor at least one surface of said web, said supplemental heating meansbeing juxtaposed with said supply for elevating the temperature of saidcovering material prior to application thereof to said surface.

8. The combination defined in claim 1 wherein said filler consistspredominantly of narrow particles. further comprising orienting means atsaid throat for positioning said particles in said stream generallytransversely to the direction of motion of said conveyor bands.

1. In an apparatus for making pressed board from thermosetting resinousmaterial and filler, in combination: a pair of perforated, endlessconveyor bands with generally horizontal, relatively inclinedconfronting surfaces forming a converging throat between them; nozzlemeans adjacent said conveyor bands for continuously blowing asubstantially horizontal stream of thermosetting resinous material andfiller entrained by a carrier fluid into said throat from the broad endthereof; heating means at said throat for at least partly setting saidresinous material during compaction of the mixture between said conveyorbands into a continuous and coherent web; a continuously operating pressadjoining said conveyor bands at the narrow end of said throat forreceiving said web therefrom and further compacting same with finalsetting of said resinous material; and a finishing stage insertedbetween said conveyor bands and said press, said finishing stage beingprovided with supplemental heating means for at least maintaining thetemperature of the web issuing from said throat.
 2. The combinationdefined in claim 1 wherein said conveyor bands are provided withrespective pressure plates for compacting the mixture of resinousmaterial and filler.
 3. The combination defined in claim 2 wherein saidpressure plates are provided with channels, said heating meanscomprising a source of hot fluid circulating through said channels. 4.The combination defined in claim 2 wherein said heating means comprisesa pair of electrodes connected across a high-frequency generator, saidelectrodes being constituted at least in part by said pressure plates.5. The combination defined in claim 1, further comprising guide meansfor said mixture bracketing said nozzle means and narrowing toward thebroad end of said throat.
 6. The combination as defined in claim 1wherein said heating means comprises a heater for said carrier fluidahead of said nozzle means.
 7. The combination defined in claim 1wherein said finishing stage includes a supply of covering material forat least one surface of said web, said supplemental heating means beingjuxtaposed with said supply for elevating the temperature of saidcovering material prior to application thereof to said surface.
 8. Thecombination defined in claim 1 wherein said filler consistspredominantly of narrow particles, further comprising orienting means atsaid throat for positioning said particleS in said stream generallytransversely to the direction of motion of said conveyor bands.